ABSTRACT
To evaluate the long term effects of an IUD on the human endometrium and find the possible contraceptive mechanism of IUD, histologic, histochemical and ultrastructural studies of human endometrial biopsies from 44 normal controls and 178 IUD wearers were made. Histologic findings included interstitial hemorrhage, inflammatory reaction, hyperplasia, atrophy, focal necrosis and squamous metaplasia. However, all of these findings were either infreqnent or insignificant except for inflammatory reaction. Histochemica1, enzymatic and ultrastructural findings were a1so unremarkable. The most significant finding, was asynchronism between cyclic dating and endometrial histologic dating, showing delayed endometrial maturation in the majority of IUD users. In summary, IUD insertion brings about mild and little histologic alteration in the human endometrium, but the inflammatory reaction and asynchronous endometrial matruation may play some role in the antifertility actifertility action of an IUD.